SONOGRAPHIC PREDICTION OF SHOULDER DYSTOCIA IN INFANTS OF DIABETIC MOTHERS

Objective: To determine if the difference between the abdominal diamet er and biparietal diameter (AD-BPD difference), as measured by ultraso und examination, predicts shoulder dystocia in borderline macrosomic i nfants of diabetic mothers. Methods: A retrospective study was perform ed of births occurring from January 1990 through June 1995. Eligibilit y requirements included diabetic pregnancy, ultrasound examination wit hin 2 weeks of delivery, estimated fetal weight of 3800-4200 g, and va ginal delivery. The mean AD-BPD difference was compared in normal deli veries and those complicated by shoulder dystocia, using the Student t test and by multiple regression analysis. A receiver operating charac teristic curve was generated to determine if an AD-BPD cutoff: value c ould be used clinically to predict shoulder dystocia. Results: Thirty- one patients, sh with dystocia, were eligi- ble for the study. The mea n AD-BPD differences for those with and without shoulder dystocia were 3.1 and 2.6 cm, respectively, a statistically significant difference (P = .05). Comparing the groups with and without shoulder dystocia, no significant differences could be found in mean age, parity, weight, b irth weight, or gestational age. Shoulder dystocia occurred in six of 20 patients (30%) in whom the AD-BPD difference was at least 2.6 cm bu t in none of 11 patients in whom it was less than 2.6 cm, also a stati stically significant difference (P = .05). Conclusions: The AD-BPD dif ference was greater in borderline macrosomic fetuses of diabetic mothe rs who experienced shoulder dystocia than in those who had uncomplicat ed vaginal deliveries. Applying an AD-BPD cutoff value of 2.6 cm to th is population prospectively would have provided excellent sensitivity, specificity, and predictive value in identifying those fetuses at hig h risk for birth injury.